It has applications in a wide variety of fields, including connecting an element to a substrate, in particular a substrate on which no attachment element was initially provided, or further reinforcing structures that need to be made stronger in order to repair or prevent the appearance of structural defects.
Metal elements are often assembled on a metal substrate by welding. This technique requires a large temperature increase, which is propagated due to the thermal conductivity of the metal substrate. It is sometimes prohibited due to environmental incompatibilities, for example if there is a flammable atmosphere near the assembly zone. Its implementation can also be problematic if the structure comprising the substrate has paint or other coatings that deteriorate at high temperatures, as the welding of the element then leads to the need to reapply the paint or coating, which can be time-consuming and costly.
For these reasons, welding techniques pose serious problems on offshore platforms or ships or pipelines carrying hydrocarbons or other flammable substances. They are commonly used but have the drawback of requiring a suspension of operation that can vary in length, together with sometimes restrictive measures to ensure the required level of safety. Welding techniques are also very difficult to implement under water or in the tidal zone.
Another solution is to bond the element to the substrate by means of a thermosetting or thermoplastic adhesive. A difficulty in this case is to guarantee that the desired properties of the adhesive are obtained. Generally, suppliers characterise the properties of the adhesives when they are implemented under well-controlled conditions, particularly in terms of temperature, degree of humidity, etc. These conditions are not necessarily all present in practice, particularly during operations in a marine environment. Furthermore, it is extremely difficult to guarantee the durability of the adhesive if the environment is relatively aggressive, which is also unfavourable to operations in a marine environment.
Structures are sometimes strengthened by applying a metal or composite reinforcement to the structure. However, similar problems to those set out above arise if an element is bonded to a substrate. In the case of a metal type reinforcement, it is connected to the structure by means of an adhesive, such as a resin. The composite material usually comprises a resin that acts as an adhesive in particular, and it is difficult to guarantee its satisfactory performance if it is applied in poorly-controlled conditions. The composite material can deteriorate over time if the reinforcement is in an aggressive environment. The same applies to the adhesive if a metal reinforcement is used. The reinforcement imparted to the structure is not therefore durable.